function [out] = append_backslash(in,u)
% append a backslash to the input argument if there isn't one already
if(nargin > 1)
   bksl = slash4OS('/');
else
   bksl = slash4OS('\');
end;
in = slash4OS(in);
a=findstr(in, bksl);
l=length(a);
if(l == 0 | a(l) < length(in))   
   out=strcat(in, bksl);
else
   out = in;
end
